The compound of the following Chemical Formula 1 is first disclosed in Korean Patent Publication No. 10-2014-0022229 filled on Aug. 13, 2012. The compound of Chemical Formula 1 is described as Chemical Formula 17 in the Patent Document, but crystalline modifications of the compound of Chemical Formula 1 are not described.

Specific crystalline substances, i.e., structures or polymorphic forms of a pharmaceutical compound may be objects of interest to those involved in the development of suitable dosage forms. This is because the precise dosage used or measured for one type of structure or form may not be applicable to another type of structure or form when a specific crystalline or polymorphic form is not maintained consistent during clinical and stability studies.
Once a pharmaceutical compound has been prepared for use, it is important to identify the structures or polymorphic forms that are carried in each dosage form to maintain the same form in manufacturing process and ensure that the same amount of drug is contained in each dosage. Thus, it is desired to ensure that there is a consistent structure or polymorphic forms, or a consistent combination of structures or polymorphic forms. In addition, characteristic structures or polymorph forms may exhibit enhanced thermodynamic stability and may be more suitable than other structures or polymorphs to be included in pharmaceutical formulations.
In the present application, reference to any literature does not constitute admission to prior art related to the present application.